Occurrence of tongue worm, Linguatula cf. serrata (Pentastomida: Linguatulidae) in wild canids and livestock in south-eastern Australia

Pentastomids are obligate zoonotic arthropod parasites utilising canids and vulpids as their definitive hosts and several herbivorous species as their intermediate hosts. Reported only 10 times in Australia over the last 150 years as incidental findings, adult Pentastomids referred to as Linguatula serrata have been encountered in nasal cavities of domestic and wild dogs, and foxes. Nymphs have been reported in cattle and rabbits. In the present study, a number of potential definitive hosts, including red foxes (Vulpes vulpes), wild dogs (Canis lupus dingo and C.l. dingo x C. familiaris) and feral cats (Felis catus), and intermediate hosts cattle (Bos taurus), sheep (Ovis aries), feral pigs (Sus scrofa), rabbits (Oryctolagus cuniculus), goats (Capra hircus) and a European hare (Lepus europaeus), from the highlands of south-eastern Australia were examined. Of the animals examined 67.6% of wild dogs (n = 37), 14.5% of red foxes (n = 55) and 4.3% of cattle (n = 164) were found to be infected with Pentastomids, herein identified as Linguatula cf. serrata. The common occurrence of the parasite in wild dogs and less frequently in foxes suggests these wild canids have potential to act as a reservoir for infection of livestock, wildlife, domestic dogs and possibly humans. The unexpected high frequency of the parasite in wild dogs and foxes in south-eastern Australia suggests the parasite is more common than previously realised. Of the potential intermediate hosts in the region, only 4.3% of cattle were found to be infected with pentastomid nymphs which suggest the search for the host(s) acting as the main intermediate host in the region should continue. Future studies should investigate transmission patterns, health impacts on hosts and whether the parasite has zoonotic significance in Australia.